[sdiy] 2164 Korgasmatron VCF

[Harry Bissell]

I have the EFM version as well... the diodes are in the wrong place in that design
and they do not clip symmetrically. (the original used the diodes around an opamp, the
EFM has an OTA in that position)> The feedback is taken from a different point as well.

Somewhere I have a copy of the schematic that I marked up, its also possible that there
is some copy in the EFM archives.

I know of many ways to 'dial a  zener' but I'm hoping that David has a new and elegant
solution :^)

H^) harry


----- Original Message -----
From: Benno <benalog77 at gmail.com>
To: Harry Bissell <harrybissell at wowway.com>
Cc: David G. Dixon <dixon at interchange.ubc.ca>, 'Synth DIY' <synth-diy at dropmix.xs4all.nl>
Sent: Thu, 12 Aug 2010 09:37:54 -0400 (EDT)
Subject: Re: [sdiy] 2164 Korgasmatron VCF

I've been wondering the same thing. I've got my old dual EFM module i modified so one filter has the 3 anti-parallel diodes, the other is without and they both sound very different winding up the resonance. it would be good to be able able to control the middle ground between the two.

ben.
On 12/08/2010, at 10:20 PM, Harry Bissell wrote:

> I don't know if you posted any details before... but what is your
> "dial in a zener voltage" method. Is it just adding series resistance
> or something more complex ?
> 
> H^) harry
> 
> 
> ----- Original Message -----
> From: David G. Dixon <dixon at interchange.ubc.ca>
> To: 'Synth DIY' <synth-diy at dropmix.xs4all.nl>
> Sent: Thu, 12 Aug 2010 00:29:10 -0400 (EDT)
> Subject: Re: [sdiy] 2164 Korgasmatron VCF


-- 
Harry Bissell & Nora Abdullah 4eva